This invention relates to a hand held pneumatic hydraulic power unit that may be used for setting rivets, shearing, forming, punching, etc.; this disclosure relating to its use as a riveting tool.
While hand held riveting tools are well known, the tool of the subject invention incorporates certain features which provide advantages over known tools of the prior art.
More particularly, the tool of the subject invention eliminates the need for a separate hydraulic power unit for delivery of pressurized hydraulic medium to the tool, thus, among other things, avoiding loss of power in fluid conducting hoses associated with such an arrangement.
The tool of the subject invention can be of lighter weight than a pneumatic hand held riveting tool of the same maximum force riveting capacity.
Another feature of the tool of the present invention is a throttle valve arrangement wherein the rivet setting piston can be moved to rivet contact position before full riveting pressure is applied, thus, allowing accurate contact rivet alignment prior to a rivet squeezing operation.
Another feature of the tool of the present invention is that movement of the throttle valve to the non-operative position during any part of the power stroke or in the stall condition results in rapid movement of the piston in the hydraulic cylinder away from the rivet setting position.
The tool of the present invention can be provided either with a "C" type riveting yoke, or an alligator type riveting yoke, the latter being arranged to provide the same output force regardless of reach, such being accomplished by a different mechanical advantage in each size. In pneumatic type riveters using a wedge and roller arrangement in an alligator type yoke, the riveting pressure decreases as the reach (length) increases.
A further feature of the tool of the present invention is a throttle lever safety arrangement whereby the throttle lever must be pushed forward before it is in tool operative condition.
Still another feature is that full tool pressure can be applied at all times to the rivet throughout the entire rivet setting operation until power cutoff.